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1 Carnot, Nicolas Léonard Sadi
SUBJECT AREA: Steam and internal combustion engines[br]b. 1 June 1796 Paris, Franced. 24 August 1831 Paris, France[br]French laid the foundations for modern thermodynamics through his book Réflexions sur la puissance motrice du feu when he stated that the efficiency of an engine depended on the working substance and the temperature drop between the incoming and outgoing steam.[br]Sadi was the eldest son of Lazare Carnot, who was prominent as one of Napoleon's military and civil advisers. Sadi was born in the Palais du Petit Luxembourg and grew up during the Napoleonic wars. He was tutored by his father until in 1812, at the minimum age of 16, he entered the Ecole Polytechnique to study stress analysis, mechanics, descriptive geometry and chemistry. He organized the students to fight against the allies at Vincennes in 1814. He left the Polytechnique that October and went to the Ecole du Génie at Metz as a student second lieutenant. While there, he wrote several scientific papers, but on the Restoration in 1815 he was regarded with suspicion because of the support his father had given Napoleon. In 1816, on completion of his studies, Sadi became a second lieutenant in the Metz engineering regiment and spent his time in garrison duty, drawing up plans of fortifications. He seized the chance to escape from this dull routine in 1819 through an appointment to the army general staff corps in Paris, where he took leave of absence on half pay and began further courses of study at the Sorbonne, Collège de France, Ecole des Mines and the Conservatoire des Arts et Métiers. He was inter-ested in industrial development, political economy, tax reform and the fine arts.It was not until 1821 that he began to concentrate on the steam-engine, and he soon proposed his early form of the Carnot cycle. He sought to find a general solution to cover all types of steam-engine, and reduced their operation to three basic stages: an isothermal expansion as the steam entered the cylinder; an adiabatic expansion; and an isothermal compression in the condenser. In 1824 he published his Réflexions sur la puissance motrice du feu, which was well received at the time but quickly forgotten. In it he accepted the caloric theory of heat but pointed out the impossibility of perpetual motion. His main contribution to a correct understanding of a heat engine, however, lay in his suggestion that power can be produced only where there exists a temperature difference due "not to an actual consumption of caloric but to its transportation from a warm body to a cold body". He used the analogy of a water-wheel with the water falling around its circumference. He proposed the true Carnot cycle with the addition of a final adiabatic compression in which motive power was con sumed to heat the gas to its original incoming temperature and so closed the cycle. He realized the importance of beginning with the temperature of the fire and not the steam in the boiler. These ideas were not taken up in the study of thermodynartiics until after Sadi's death when B.P.E.Clapeyron discovered his book in 1834.In 1824 Sadi was recalled to military service as a staff captain, but he resigned in 1828 to devote his time to physics and economics. He continued his work on steam-engines and began to develop a kinetic theory of heat. In 1831 he was investigating the physical properties of gases and vapours, especially the relationship between temperature and pressure. In June 1832 he contracted scarlet fever, which was followed by "brain fever". He made a partial recovery, but that August he fell victim to a cholera epidemic to which he quickly succumbed.[br]Bibliography1824, Réflexions sur la puissance motrice du feu; pub. 1960, trans. R.H.Thurston, New York: Dover Publications; pub. 1978, trans. Robert Fox, Paris (full biographical accounts are provided in the introductions of the translated editions).Further ReadingDictionary of Scientific Biography, 1971, Vol. III, New York: C.Scribner's Sons. T.I.Williams (ed.), 1969, A Biographical Dictionary of Scientists, London: A. \& C.Black.Chambers Concise Dictionary of Scientists, 1989, Cambridge.D.S.L.Cardwell, 1971, from Watt to Clausius. The Rise of Thermodynamics in the Early Industrial Age, London: Heinemann (discusses Carnot's theories of heat).RLHBiographical history of technology > Carnot, Nicolas Léonard Sadi
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2 Girard, Philippe de
SUBJECT AREA: Textiles[br]b. 1775 Franced. 1845[br]French developer of a successful flax-heckling machine for the preparation of fibres for power-spinning.[br]Early drawing and spinning processes failed to give linen yarn the requisite fineness and homogeneity. In 1810 Napoleon offered a prize of a million francs for a successful flax-spinning machine as part of his policy of stimulating the French textile industries. Spurred on by this offer, Girard suggested three improvements. He was too late to win the prize, but his ideas were patented in England in 1814, although not under his own name. He proposed that the fibres should be soaked in a very hot alkaline solution both before drawing and immediately before they went to the spindles. The actual drawing was to be done by passing the dried material through combs or gills that moved alternately; gill drawing was taken up in England in 1816. His method of wet spinning was never a commercial success, but his processes were adopted in part and developed in Britain and spread to Austria, Poland and France, for his ideas were essentially good and produced a superior product. The successful power-spinning of linen thread from flax depended primarily upon the initial processes of heckling and drawing. The heckling of the bundles or stricks of flax, so as to separate the long fibres of "line" from the shorter ones of "tow", was extremely difficult to mechanize, for each strick had to be combed on both sides in turn and then in the reverse direction. It was to this problem that Girard next turned his attention, inventing a successful machine in 1832 that subsequently was improved in England. The strick was placed between two vertical sheets of combs that moved opposite to each other, depositing the tow upon a revolving cylinder covered with a brush at the bottom of the machine, while the holder from which the strick was suspended moved up and down so as to help the teeth to penetrate deeper into the flax. The tow was removed from the cylinder at the bottom of the machine and taken away to be spun like cotton. The long line fibres were removed from the top of the machine and required further processing if the yarn was to be uniform.When N.L.Sadi Carnot's book Réflexions sur la puissance motrice du feu, was published in 1824, Girard made a favourable report on it.[br]Further ReadingM.Daumas (ed.), 1968, Histoire générale des techniques, Vol. III: L'Expansion duMachinisme, Paris.C.Singer (ed.), 1958, A History of'Technology, Vol. IV, Oxford: Clarendon Press. T.K.Derry and T.I.Williams, 1960, A Short History of Technology from the EarliestTimes to AD 1900, Oxford.W.A.McCutcheon, 1966–7, "Water power in the North of Ireland", Transactions of the Newcomen Society 39 (discusses the spinning of flax and mentions Girard).RLH
См. также в других словарях:
Sadi Carnot (physicien) — Pour les articles homonymes, voir Carnot et Sadi Carnot. Sadi Carnot Sadi Carnot en uniforme de polytechnicien peint par Louis Léopold Boilly … Wikipédia en Français
Nicolas Carnot — Sadi Carnot (physicien) Ne doit pas être confondu avec Sadi Carnot (président). Pour les articles homonymes, voir Carnot … Wikipédia en Français
Nicolas Léonard Sadi Carnot — Sadi Carnot (physicien) Ne doit pas être confondu avec Sadi Carnot (président). Pour les articles homonymes, voir Carnot … Wikipédia en Français
Sadi carnot (physicien) — Ne doit pas être confondu avec Sadi Carnot (président). Pour les articles homonymes, voir Carnot … Wikipédia en Français
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